One of the ISB's top members was Agent Kallus, who worked in both the Investigation and Internal Affairs branches of the organization and searched for signs of disloyal activity or insurgency. His primary mission was to ensure it did not spread into a full-scale rebellion against the Empire.[12] In the fifteenth year of the Empire, the Imperial Security Bureau took special interest in the Lothal-based Spectres rebel cell, whose attacks on Imperial outposts revealed risks of sedition and gave warning signs of rebellion.[13] Kallus became a perennial foe of the Spectres before striking an unlikely friendship with the Lasat Spectre Garazeb Orrelios, which led to reconsider his allegiance to the Empire.[14] Kallus subsequently became the rebel operative known as Fulcrum, who supplied the Phoenix Squadron and Spectres with intelligence.[15]

Later, Kallus helped the Spectres to steal Thrawn's TIE/D Defender blueprints from the Imperial Armory Complex on Lothal. This led Thrawn to realize that the rebels had a mole within the Imperial ranks.[17] Thrawn began screening the local Imperial sector command for the spy with the help of Yularen. To avoid discovery, Kallus framed LieutenantYogar Lyste. Despite Kallus' efforts, Thrawn realized that Kallus was the true spy but allowed him to continue operating in order to find Phoenix Squadron's rebel base.[18] Thrawn subsequently tricked Kallus into exposing the location of Chopper Base by disclosing information about the Rebel Alliance's plans to attack the Imperial Armory Complex. However, Kallus managed to escape during the Battle of Atollon and officially joined the Alliance.[19]

Another ISB agent was loyalty officerSinjir Rath Velus, who was recruited by ISB officerSid Uddra. After a brutal period of training on the ocean world of Virkoi, Velus personally interrogated the traitorous Imperial Navy officer LieutenantAlster Grove, who was part of a cabal that sought to assasinate Darth Vader. Velus interrogated Grove, who revealed his fellow conspirators. While Vader executed the other conspirators, Uddra threw Grove to his death in Virkoi's oceans.[9]

By 28 ABY,[25] the Imperial Security Bureau had ceased to exist along with the "Old Empire". One former ISB officer was Arliz Hadrassian, a small-time businesswoman who was the leader of the Amaxine warriors; a paramilitary faction that served as a front group for the First Order,[26] a remnant of the Old Empire based in the Unknown Regions.[27] During a meeting with the Centrist senator Ransolm Casterfo, Hadrassian spent hours regaling the young senator with stories about her career in the Imperial Military and the ISB; unaware that he was part of Senator Leia Organa's investigation into the Amaxine warriors.[26]

Agent Kallus, wearing the distinctive helmet of the ISB, designed to symbolize their status and instill fear within opponents.

The Imperial Security Bureau was a sister agency and rival to Imperial Intelligence.[5] The ISB worked closely with Emperor Palpatine, being led five years into his reign by a Bureau Chief under which served Deputy DirectorHarus Ison and Colonel Yularen, who often operated in conjunction with the Joint Chiefs. ISB was sometimes attached to various fleets, sometimes falling under the command of the Navy and working alongside Naval intelligence. Members of the ISB worked from the ISB Central Office as part of the Federal District on Coruscant, while agents in the field would constantly provide intelligence updates to headquarters.[3] The ISB high command governed the ISB. Many military officers feared the group and its power.[4]

Prospective ISB personnel were drawn from the Imperial Academy system, and given training within the ISB Academy and Offices complex, located within the Verity District on Coruscant. Members went through a training regimen which included the learning of xenophobic propaganda, and were taught from the ISB Loyalty Manual.[7] Members of the ISB were taught a specialized vocabulary to prevent outsiders from understanding their conversations. The term "auditing" was used to signal that suspects knew they were being investigated. The practice of provoking a suspect to commit a crime was referred to as "crustbusting," and interrogating a supposed innocent in hopes he or she would react suspiciously was known as "scattering." Framing a wanted suspect for a crime to make sure he or she would be arrested was referred to as "Jabba."[2]

High-ranking ISB agents could command stormtrooper squads, override orders of civilian and military authorities, replace questionable officers and commandeer Imperial military hardware, including Star Destroyers.[2] Loyalty officers of the ISB[28] were tasked with ensuring that regular troops and officers obeyed orders and conformed to Imperial ideology, and were regarded with great fear and respect. Impromptu inspections, undercover surveillance and seemingly limitless authority gave such officers unprecedented access to the lives of regular servicemen, creating a culture of fear to deter any tenuous links within the chain of command.[24][7]

Operatives in the Surveillance branch were by far the most numerous, with its members focused on deciphering encrypted information and analyzing data to screen for potential threats against the New Order.[2]

Interrogation was the second largest branch in the ISB, and was intent on extracting information from various lifeforms to obtain valuable information. It claimed to have a 95 percent success rate in recovering useful data from questioned subjects.[2] To that end, the ISB notably used IT-O Interrogation Units[29] developed by the Imperial Department of Military Research.[30]

The Re-Education division was focused on what some would call 'brainwashing' its subjects into supporting the Galactic Empire and its actions across the galaxy.[2]Project Unity consisted of re-educating elements of society resistant to the New Order through a process of psychological manipulation and pharmaceutical conditioning.[31]

The Internal Affairs division maintained order by investigating possible instances of insubordination within the Empire, with Yularen briefly heading a division dedicated to exposing sedition within the Imperial Senate before becoming Deputy Director of the Naval Intelligence Agency.[3][2] In addition, a single Internal Affairs officer was stationed aboard all Star Destroyers to investigate any signs of sedition among the crew.[20]